Countless agricultural and industrial apparatus utilize hydraulic piston and cylinder devices to move machinery sections or to position a portion of the apparatus near the work surface, etc. Agricultural and construction machinery in particular requires such devices to be sturdy, trouble-free and without complex electrical or fluidic control devices which are not suitable for rough use or field service. In many cases, the space available for the cylinder is an important factor which further increases the need for a rugged, compact and maintenance-free hydraulic device. Many installations require that the stroke of the piston, and thus the position of the load, be adjustable in the field. While many complex hydraulic or electrical devices are capable of programming a fluid operated cylinder, their cost and complexity make them unsuitable for many installations and unsuitable for field adjustment or servicing by the machinery operator.
This invention relates to a fluid pressure cylinder having an adjustable stroke length for use in moving agricultural or other industrial machinery components. More particularly, the invention is suited for use with a double-acting hydraulic cylinder used on agricultural or industrial machinery in which the cylinder is secured to the frame of the machinery and the reciprocating piston is secured to and operates a movable load, such as a harvesting mechanism, moving blade, etc. The invention is particularly suited for this purpose in that it provides a cylinder of minimum dimensions and external components which can be readily and simply adjusted to position its load at a predetermined position by means of a self-contained valve mechanism built into the head of the cylinder.